Belfast road network changed to 20mph

Belfast city center implementation zone

Belfast metropolitan area

Belfast’s control zone

Time series Analysis

Mapping accidents with roads: 2013

##   a_speed a_ID
## 1      30   59

Mapping accidents with roads: 2014

##   a_speed a_ID
## 1      30   84

Mapping accidents with roads: 2015

##   a_speed a_ID
## 1      20    2
## 2      30   86

Mapping accidents with roads: 2016

FALSE   a_speed a_ID
FALSE 1      20   28
FALSE 2      30   51

Mapping accidents with roads: 2017

FALSE   a_speed a_ID
FALSE 1      20   26
FALSE 2      30   59

Mapping accidents with roads: 2018

##   a_speed a_ID
## 1      20   28
## 2      30   47

Mapping accidents with roads: 2019

##   a_speed a_ID
## 1      20   21
## 2      30   52

Count pre 20mph

##   a_speed a_ID
## 1      20    2
## 2      30  236

Count post 20mph

##   a_speed a_ID
## 1      20  103
## 2      30  202

Output column: Changed to 20 mph

##   Urban_Rural a_ctype CLASS              NAME ROAD_NUMBE
## 1       RURAL      13     A       YORK STREET      A0002
## 2       RURAL      13     A       YORK STREET      A0002
## 3       RURAL      13     A       YORK STREET      A0002
## 4       RURAL      13     A       YORK STREET      A0002
## 5       URBAN      13     A       YORK STREET      A0002
## 6       URBAN       2     A CHICHESTER STREET      A0020

Mapping accidents with zones( metropolitan area) : 2013

Mapping accidents with zones ( metropolitan area): 2014

Mapping accidents with zones ( metropolitan area) : 2015

Mapping accidents with zones ( metropolitan area) : 2016

Mapping accidents with zones ( metropolitan area) : 2018

Mapping accidents with zones ( metropolitan area) : 2019

Total accidents in the implementation zone

## [1] 7268

Table: Average annual road traffic collision rates in the metropolitan area of Belfast

Table 1: Average annual road traffic collision rates in the city of Belfast (PSNI data)
Type collisions pre-20mph (2013 / 2016 - 3 years) collisions post-20mph (2016 / 2019 - 3years & 11 months) rate pre-20mph rate post-20mph diff in rates = pre - post Perc.diff.rates = (pre - post) / pre * 100
Streets changed
Streets changed to 20mph 238 305 79.33 77.81 1.52 2
Streets stayed
20mph, 30mph 3630 4576 1210.00 1167.35 42.65 4
All streets
All streets 3868 4881 1289.33 1245.15 44.18 3
Note:
1 All accidents at 20mph, 30mph

Table: Average annual road traffic collision rates in the city centre of Belfast

Table 1: Average annual road traffic collision rates in the city of Belfast (PSNI data)
Type collisions pre-20mph (2013 / 2016 - 3 years) collisions post-20mph (2016 / 2019 - 3years & 11 months) rate pre-20mph rate post-20mph diff in rates = pre - post Perc.diff.rates = (pre - post) / pre * 100
Streets changed
Streets changed to 20mph 237 305 79.00 77.81 1.19 2
Streets stayed
20mph, 30mph 329 432 109.67 110.20 -0.53 0
All streets
All streets 566 737 188.67 188.01 0.66 0
Note:
1 All accidents at 20mph, 30mph

Effect estimate ( GIS )

Effect estimate
Tax year 2013/14 2014/15 2015/16 2016/17 2017/18 2018/19 2019/20
Annual number of collisions in roads changed to 20mph 194 182 190 182 191 190 174
Rate per year 194 182 190 182 191 190 193.33
% reduction in collisions -1.06
Calculations
A + B + C / 3 188.67
D + E / 3.9 188.97
A - B / A 6.00
B - C / B -4.00
Unadjusted_estimate 0.00
Secular_trend 1.00
Note:
1 A : accidents 2013/14 ( 1 year )
2 B : accidents 2014/15 ( 1 year )
3 C : accidents 2015/16 ( 1 year )
4 D : accidents 2018/19 ( 1 year )
5 E : accidents 2019/20 ( 11 months )

Count accidents in Control Zone : City Center –> Central ( Ards )

## [1] 175

Output column : Output Area code ( OA_code )

##    Urban_Rural a_ctype    OA_CODE
## 8        URBAN      13 95GG390015
## 10       URBAN      13 95GG390011
## 12       URBAN       2 95GG390015
## 22       URBAN      13 95GG390015
## 32       URBAN      13 95GG350001
## 39       RURAL      13 95GG200003